This invention relates to a robot server assembly for serving table tennis balls, and more specifically to a robot server assembly that is collapsible, portable, and employs a unique dual net feature to capture balls hit back at the robot so as to allow the balls to be fed to the server and reused.
Table tennis is a popular, competitive and recreational sport. The object of the game is to have a player on each side of the table so that each player can serve, return and rally a table tennis ball. Often, however, a player may wish to play the game of table tennis without another player. To that end, various table tennis ball serving devices or robots have been developed. The devices serve the ball to the player so that the player can return the shot in the direction of the robot. Many of the devices known to the art, however, lack functional useful or effective means of capturing the ball returned by the human player and recycling the ball to the robot server.
For example, U.S. Pat. No. 2,087,575 to Littell et al. describes a device that can be employed in table tennis, for example, for ejecting light weight balls. The device includes an overhead supply means, typically in the form of an overhead hopper which is fed by a conveyor system having a series of ball carrying members mechanically mounted for movement in a continuous loop.
U.S. Pat. No. 2,508,461, to Lemon describes an apparatus for ejecting table tennis balls and employs pressurized air, as from a home vacuum cleaner, to propel and eject balls from a conduit. A gravity fed collector box is provided for introducing a ball into a lower portion of the conduit. The Lemon device provides no control on the entrance of the balls, and failure of the balls to feed properly can result in a loss of air pressure particularly as a plurality of balls are introduced into the system.
U.S. Pat. No. 3,917,265, to Schrier, is another pneumatic ball ejecting machine including pneumatic means for transporting the balls from a collection source, for loading the balls to an ejection means and for ejecting the balls. Again, maintenance of air pressure in the device is critical. Furthermore, the device does not disclose an effective means for catching the return shot and feeding it to the ejector mechanism.
U.S. Pat. No. 4,116,438 to Berliner, describes a device for throwing table tennis balls, having a mechanical throwing means including two flexible, thin throwing discs extending generally parallel with respect to each other for grasping a table tennis ball between them and ejecting it along a guide. The balls are returned to the serving disc by pneumatic means.
U.S. Pat. No. 2,793,636 to Cook, describes a fan operated device as does U.S. Pat. No. 3,911,888 to Horvath.
U.S. Pat. No. 3,989,242, to Augustine, discloses a device for ejecting conventional tennis balls and also discloses an enclosure means including netting for catching served balls hit by a player.
My own U.S. Pat. No. 3,794,001, to Newgarden, describes a relatively simple device for imparting variations in the amount of spin applied to a ball being served by the server. The disclosure of my patent is intended to be incorporated herein by reference.
I am also a joint inventor of U.S. Pat. Nos. 4,844,458; 4,854,588; 4,917,380; and 5,009,421 which discloses a portable table tennis serving device including a robot server and a ball capture net. This device employs the use of one collapsible net which cooperates with the robot so that returned balls are fed automatically to the robot. A folding net structure is also employed for attachment to a table tennis table and for feeding balls to a robot ball server. The single net structure includes a plurality of arms extending radially from a central member and netting suspended between the arms. The netting has a lower edge which is cooperatively connected with a trough device for receiving balls that fall from the netting. The trough is disposed to feed the balls to the robot serving device. The disclosures in the above described patents are incorporated by reference herein.
It can be seen that, for the most part, the robot serving devices of the prior art do not disclose ball catching mechanisms. Those table tennis balls serving assemblies which do include catch nets commonly employ a single net design where the ball strikes the net and drops into a trough so that the ball can be fed back to the robot.
Several problems are involved with such ball catching assemblies of the prior art. First of all, such devices employ a standard single net construction. The net is suspended behind the robot serving device. When the robot serving device serves the ball, the player can strike the ball back at the net. However, a returned ball that strikes the single net configuration under high velocity can bounce off of the net back onto the playing surface, or can carom off of the net onto the floor. The prior art single net configurations are more convenient than no catch net at all; however, they are not entirely effective at stopping all shots for capturing balls and feeding them back to a robot server. Also, the robot server is often mounted toward the front of the device so that it protrudes out of the netting and is precariously close to the table itself. With such designs, the returned balls often strike the exposed robot and bounce out of play. Moreover, the robot can intrude upon table space required for the game.
Robots work best with table tennis balls of the proper diameter and near perfect roundness. Misshapened or large balls can cause the robot to jam or malfunction and cause excessive wear. Robot assemblies of the prior art do not provide a means for eliminating bad balls before loading them in the devices.
Furthermore, although the nets of the previous designs are intended to be collapsible, or foldable, the designs do not allow them to be completely folded into a convenient configuration for carrying. Even when folded, the nets of the prior art assembly extend outward from the base of the robot so as to be inconvenient for storage. Assemblies known to the prior art have awkward and complex mechanism for attaching the assembly to the table. The prior art assemblies are not designed for ease of storage and carrying and lack effective means for keeping all components of the assembly, as well as the table tennis balls used with the assembly, together in one group and as compact unit when not in use.